"This freezes onto the rails of the sled and onto the dogs' legs, so each time we run through it we have to stop, hack the ice off the sled with an axe [and] try to get the dogs as free from the ice as possible," explained Mr Oakley on his blog.

He said that by 1 March they were "cold, wet and very miserable", with no fire.

Three days later, after crossing a vast frozen lake that "creaked and groaned" as they went over it, they crossed the border into Alaska.

The going was easier as they headed southwards despite a snowstorm that left them huddled in tents for a day.

By last week the weather was warmer and the dogs had to stop periodically because the -7C temperatures left them overheated.

The team made it to Eagle (population 86) with "only mild frostbite on various fingers and toes" and the dogs in good condition.

Image copyrightRoyal Geographical SocietyImage caption
The team (Mr Oakley second from left) celebrate their arrival in Eagle

"What amazing dogs these have been!" said Mr Oakley. "What a feat of endurance to have pulled a heavy sledge 700 miles in bitter temperatures over extreme terrain and still be wagging their tails every morning."

Roald Amundsen

Image copyrightHulton GettyImage caption
In 1911, Roald Amundsen became the first person to reach the South Pole

Born in Norway in 1872, Amundsen was the first explorer to reach the South Pole and to circumnavigate the Arctic. He was also the first person to sail through the Northwest Passage - sledging south from Herschel to Eagle where he sent a telegram announcing the feat.

In the 1920s he began making trips towards the North Pole with varying success. He flew across the Arctic in 1925 and again later in an airship.

Amundsen disappeared in 1928 after he flew to the rescue of a ship lost in the Arctic.

Mr Oakley said he was looking forward to enjoying a "glass of wine and a decent meal" with his family in Fulham.

He added: "I'm not going to give up yet. I'll be 67 this year and I reckon I've got a few more in me yet. Another big one."